Technical Field
This application relates to the field of display, and in particular, to a method and a structure for generating a picture compensation signal, and a restoring system.
Related Art
With rapid development of the display technical industry, liquid crystal displays have become mainstream products in recent years. Under the propel of user needs and industrial competition pressure, the liquid crystal displays have been widely used in electronic products in people's daily life, such as television sets, computers, mobile phones, and tablets, daily used by people, due to the advantages of having a high resolution and a high luminance, not having geometric distortion, and meanwhile having a small volume, a light weight, and a low power consumption. In addition, a panel display module is a main component of a liquid crystal display. The manufacturing process of the panel display module is complex and nearly one hundred of processes are needed; and therefore, various display defects may inevitably appear in the manufacturing process. A relatively common defect among the display defects is mura defect. The mura defect means different colors or difference in luminance sensed visually caused by various traces generated by unevenness in luminance of a display panel under the same light source and the same ground color. Whether there is mura in the display panel can be determined by switching the display panel to a black screen and other low grayscale screens in a darkroom and then observing from different angles to determine whether there are traces in the display screen. Such the traces may be horizontal stripes or stripes at an angle of 45°, may be a straightly-cut square block or a block appearing at a corner, or may be traces without a rule to follow at all. A display region where the various traces appear is generally referred to as mura. The mura brings about visual discomfort for people and severely influences and reduces the quality grade of the panel.
In recent years, with spread of 4K and 2K televisions, the mura phenomenon becomes severe, and the demura technology is raised to the occasion. At present, by using the technology, data to be compensated is calculated by comparing difference between luminance in other regions of a panel and that of a reference point, to finally achieve evenness in luminance of the whole panel. Expression of mura may vary with respect to luminance of different grayscales. Therefore, the demura at present is performed with respect to three fixed sampling grayscales, generally 10%, 30%, and 70%, and compensation values for the other grayscales are obtained through linear operation by using the three grayscales. However, because the mura has complex and varied states and some types of mura are obvious at some grayscales only, the algorithm using fixed grayscales at present may cause inaccurate compensation and poor effect.
The working principles of demura sampling at present are set for ease of use of a system, and a demura system does not distinguish the mura can be seen in which grayscale screen, but only photograph screens of three input grayscales of 10%, 30%, and 70% fixedly, to obtain compensation values in the three grayscales, respectively. Compensation values for the other intermediate grayscales are simply obtained through linear operation. The disadvantages of the method at present can also be predicted. If the mura of a display device can be seen in a grayscale from 30%, by using such the linear operation, not only a good compensation effect cannot be obtained, but also adverse effect is caused for low grayscales in which mura cannot be seen originally.